Packages are simply folders under Packages, or zip archives with the
.sublime-package extension saved under InstalledPackages.

Here’s a list of typical resources that can be found inside packages:

build systems (.sublime-build)

key maps (.sublime-keymap)

macros (.sublime-macro)

menus (.sublime-menu)

plugins (.py)

syntax preferences (.tmPreferences)

settings (.sublime-settings)

syntax definitions (.tmLanguage)

snippets (.sublime-snippet)

themes (.sublime-theme)

Some packages may include support files for other packages or core features.
For example, the spell checker uses $PATH_TO_SUBLIME_TEXTPackagesLanguage -
English.sublime-package as a data store for English dictionaries.

In this guide, we classify packages under different categories. This
classification is artificial and useful just for clarity when discussing this
topic. Sublime Text doesn’t use this classification in any way.

core packages

Sublime Text requires these packages in order to work.

shipped packages

Included in every installation, though technically not required. They
enhance Sublime Text out of the box. May have been contributed by users or
third parties.

user packages

Installed by the user to extend Sublime Text’s functionaility. They are not
part of any Sublime Text installation, and are always contributed by users
or third parties.

installed packages

Packages stored under Installed Packages as .sublime-package‘s

It’s worth noting that by third party we mainly refer to users of other
editors, such as Textmate.

Ultimately, installing a package is simply a matter of copying a folder
containing Sublime Text resources to Packages, or a .sublime-package
file to Installed Packages. The only thing that varies is how you obtain
and copy these files.

Installing Packages vs Installed Packages

Note that installing a package doesn’t actually make that package an
installed package. Installed packages are .sublime-package files
residing in the InstalledPackages directory. In this guide, we use
to install a package to mean to copy a package to Packages.

Sublime Text can restore any package located in InstalledPackages, but
not every package located in Packages.

Packages/Default and Packages/User receive special treatment when
merging files (e.g. .sublime-keymap and .sublime-settings files).
Before merging can take place, the files have to be arranged in some order. To
that end, Sublime Text sorts them alphabetically by name, with the exception
of the Default and User folders. Files contained in Default will
always go to the front of the list, and those in User, to the end.

Sublime Text keeps a copy of all installed packages so it can recreate them as
needed. This means it can reinstall core packages, shipped packages and,
potentially, user packages alike. However, only user packages installed as
sublime-packages are added to its registry of installed packages. Packages
installed in alternative ways will be lost completely if you delete them.

To revert Sublime Text to its default configuration, delete the data directory
and restart the editor. Keep in mind that the InstalledPackages folder will
be deleted too, so you’ll lose all your installed packages.

Always make sure to back up your data before taking an extreme measure like
this one.

Reverting Sublime Text to a fresh state solves many problems that appear to be
due to bugs in Sublime Text but are in fact caused by misbehaving plugins.